Signaling circuits



R. F. SPAMER SIGNALING CIRCUITS Sept. 2, 1941.

2 Sheets-She et 1 INVENTOR R.F.SPAMER BY I ATTORNEY Filed April 5, 19 38 2 Sheets-Sheet 2 n" 3 a I m J 0 g n. 6

n 2 a 3 9 6 n a 5 a v 3 INVENTOR r R. F. SPAM ER 7 %.M

ATTORNEY Sept. 2, 1941. R. F; SPAMER SIGNALING CIRCUITS Filed April 5., 19 38 FIG.2

Patented Sept. 2, 1941 SIGNALING CIRCUITS Application April 5, 1938, Serial No. 200,146

9 Claims.

This invention relates to signal systems, and more particularly to signal systems of the type wherein a number of watchmans tour systems or fire alarm Systems are connected to a central station. It is customary in these systems to have several protected premises connected to a central station wherein an attendant can supervise watchmen or fire stations in the several premises. Each watchman periodically send signals to the central station where they are recorded and operate various indicators so that the attendant may supervise the system.

This type of service is no longer adequate in many instances because subscribers to the service frequently require that they themselves be able to supervise their protective systems or watchmen either by a record or other indication of the watchmans activity during the tour of duty. However, since there are a number of subscribers connected on a single line to the central station, the system must provide a signaling or recording means at each subscribers premises wherein only the local signals or subscribers watchmen will operate each subscribers recording means as signals are transmitted to the central station. In a system embodying the invention, therefore, each subscribers station is provided with a device for operating his own local signal, alarm or recorder when a signal is transmitted from his own premises, but this same device will not allow any other subscribers signals to be recorded or actuate the signal. It is further provided that any abnormal condition of the transmission line, which is of such a nature that signals can still be received at the central station, must not prevent the normal and exclusive acceptance of the signal on the transmitting subscribers local recording or indicating apparatus.

It is an object of this invention to provide a watchmans supervisory system or a fire alarm system which will accomplish the results out lined above.

Another object of this invention is to provide a signal system wherein a plurality of subscribers use a central station supervisory service and wherein each subscriber obtains a record or indication of the signals transmitted from only his premises to the central station.

Another object of this invention is to provide a watchmans signal system or a fire alarm system wherein a plurality of subscribers are connected to a central ofiice by a signal transmission line and wherein local signals from transmitters in the subscribers premises are automatically recorded therein, but such signals do not under any circumstances actuate the local recorder or alarm of any other subscriber.

A further object of this invention is to provide a signal system wherein a differential relay distinguishes between signals from a subscribers transmitters and those from a remote transmitter so that the local signals are automatically detected or recorded in the subscribers premises to the exclusion of signals from other subscribers stations. 1

A still further object of this invention is to provide a signaling system wherein any abnormal condition of the transmission line, which is of such a nature that signals can still be received at the central office, will not prevent the-normal and exclusive acceptance of the signal on the transmitting subscribers local apparatus.

Further objects of this invention will be apparent after consideration of the following description of the various embodiments shown in the drawings wherein:

Fig. 1 shows a complete signal system according to the invention;

Fig. 2 shows a modification of a subscribers circult; and

Fig. 3 shows another modification of a subscribers circuit.

Fig. 1 of the drawings shows the general layout of a McCulloh signaling circuit, particularly adapted for use in fire alarm systems, sprinkler or valve supervisory systems or night watch systems. The apparatus shown to the left of the line AA is the conventional central office equip-' ment used in McCulloh circuits, while everything shown to the right of the line AA pertains to the subscribers circuits. Numerals I, II and III indicate generally the subscribers circuits which consist of a differential relay 2'! and the impulse wheels 32, 34 and 31 for transmitting the McCulloh signals to the central station where they are recorded on recorders 2B, 2! of the conventional type. In order to save wiring, the substation circuits are arranged in series in the transmission line. Thus a circuit may be traced from the central office through line 23, coils 28, line 29, contacts 35 and 35, the other local transmitting stations, line 3! and coil 38 of the differential relay 21, and so on, through the subscribers premises. This arrangement gives the subscriber a record on a local recorder 45 of the activity of his watchman or in the case of a fire alarm system, there will be a record of whatever alarms are transmitted and any other desirable information. This feature of local signaling introduces a problem due to the series arrangement of the subscribers stations since it is imperative that no remote subscriber shall receive the local signals of subscriber I, for instance. The differential relay 2'! of station I eliminates the difiiculty of local and exclusive recording of the subscribers local signals.

The circuit is shown in normal condition where switch l9 completes a circuit to the ground side of the battery so that relays I and 3 are normally energized. When a watchman sends in his routine or emergency signal, he operates the transmitter wheel 32 for instance to thereby first ground the line 23 and then open the line at contacts 3536. When the ground is put on the line, a circuit can be traced from ground at the subscribers station through line 38, con-. tact wheel 32, contact 35, line 29, coil 28,.line 23 to the central station and line relay 3 to battery 43 and ground. The coil 30 is short circuited so that the diiferential relay is unbalanced and the coil 28 will actuate armature 40 and signal recorder 45, whereby the subscriber obtains a record of the watchmans signal. When the line circuit is opened, the line relays operate the recorders 20 and 2| by dropping their armatures. Dropping of the armatures connects the recorder 20 to battery 12 through lines 8 and I while recorder 2| is connected to the battery 13 through lines 13 and I1. Assuming that a watchman in the premises of subscriberII should operate a transmitterwheel a ground signal will be transmitted from the substation through line 25, coil 30 of difierential relay 21, line 3|, through the it can be determined whether it is on the line itself or Within a subscriber's premises. For example, if a ground occurs on the transmission line it cannot possibly afiect the local recording apparatus at any subscriber's premises while if the fault is within any premises, the local differential relay will remain continually operated and the recording device accordingly. Under such circumstances the subscribers watchman would notify the central station attendant of the continued operation of his local recorder and therefore the central station attendant would know that there must be a ground fault at that particular location. Also should a transmitting device stick so as to permanently ground the line, the central station attendant can, by referring to his time records for the particular subscriber, determine the exact transmitter in trouble.

The above description has been based on the assumption that all line conditions are normal, with the central oflice equipment shown in the drawings as McCulloh equipment in normal condition. Therefore it is necessary to consider the operation of the system under various conditions of line trouble. In order to illustrate the performance of the difierential relays under abnormal conditions, it is necessary to assume typical values of resistance for various parts of the circuit. The resistances 4| and 42 in the central transmitter contacts of subscriber Is station, coil 28 of differential relay 21, line 23, and line relay 3 as above. The signal from this substation will not be recorded in the premises of the subscriber I since coil 30 of diflerential relay 2! is wound oppositely to coil 28 and consequently the armature 40 will not be attracted.

From the above description it is easily seen that any number of subscribersi stations can be connected to the transmission line by means of the differential relays so that each subscriber will obtain his own signal locally but no other subscriber will receive that signal. All subscribers stations operate in the manner set forth above.

wheel a signal'is received at the central, ofiice but is not recorded on the subscribers local apparatus. The subscribers watchman should notify the central station of the failure. The central station attendant would thereby know of the existence of a fault in the ground wire of. the transmitter which was operated. For instance, when .the transmitter wheel 32 operates but does not ground the transmission line, the line is. opened and closed at contacts 35 and 3B whereby armature of relay 2'! is not picked up so that there is no recording of the signal j in the .local subscribers premises.

Further should the transmission line become grounded, the central station attendant can determine definitely the location of the fault, i. e.,

oflice ordinarily have a value of approximately 700 ohms each, while the line relays l' and 3 may be 150 ohms each. The line circuit may be assumed to have a resistance of approximately 1000 ohms which is equivalent to a 14.3 mile loopof No. 22 gauge copper wire and the differential relays at each substation may have a resistance of approximately 20 ohms.

It may be assumed that a ground condition occurs on, the transmission line between substations I and II and that the central ofiice panel is switched for McCulloh operation in response to the ground indication received at the control station, whereby switch l9 will be thrown to the right hand contact, switch IE will be thrown to the left hand contact and switch II will be thrown to the right hand contact. Thus, when a signal is transmitted from substation I, the line relay 3 will release when the line is open at the subscribers transmitter wheel contacts to thereby record the signals and there will be a ground current of approximately .079 amp. through the transmitter wheel 32, contact 35, coil 28, line 23, relay 3 to battery 43 and ground, while there will be no current through the relay coil 30 of differential relay 2'! since it will be short circuited by the ground momentarily established at break-wheel 32, contact spring 33 to the ground fault. Therefore the local signal apparatus 45 will be operated in a normal manner but no other subscriber's signal apparatus will operate. In the event that substation HI is operated the open line at the transmitter contacts will cause the relay I to release armature 2 and connect recordor 20 to battery I2 and ground through lines 8 and I5, thereby causing the signal to be recorded in recorder20. There will also be a ground curmanner as during normal line conditions, that is, the local signal apparatus of the transmitting local subscriber is always operated to the exclusion of any other subscriber's local signals.

It may now be assumed that a break in the transmission line occurs between substations II and Therefore the switch I! at the central oflice must be thrown to the left hand contact while switch I is thrown to the right hand contact and when the transmitter wheel at substation I is operated, the breaks in the line circuit will no longer operate the line relays but ground impulses in the line circuit will operate the line relay 3 at the central office to pick up armature 6, connecting recorder 2| to battery l8 and ground through lines l4 and I1 to operate the recorder 21, the ground circuit being the same as during normal line conditions. Substation II will also operate in the same manner. However, substation III will operate the line relay I when the line circuit is grounded at the transmitting wheel. ergized by the ground impulse to operate the local signal circuit. T

It may next be assumed that a ground occurs in the line circuit between substations I and II and that a break in the line occurs between substations Hand III. In this case the switches l l and I5 at the central station are both thrown to the left handcontacts. When the transmitter wheel of substation I is operated, the line relay 3 will operate on the break impulses as under normal conditions and the coil 28 of diiierential relay 2! will operate the local signal apparatus. Signals from substation No. II will not operate the central station apparatus under any conditions. When substation III is operated no signal will be transmitted over line 23, but a ground impulse will 'be transmitted through coil-23B to operate the relay I at the central office and. connect battery l2 to the recorder through lines 1 and I5.

From the above discussion of various line conditions it is evident that the system constructed in accordance with this invention will include the operating advantages of the usual McCulloh systems. However, due to the use of the differential relay 2'! and similar relays at all substations, it is found that under any conditions each subscriber obtains local indication of the performcircuit wherein the transformer is substituted for the relay 21 shown in Fig. 1.

The primary windings 5| and 52 of the transformer 50 are connected to lines 23 and 25 and to the transmitter wheel whereby the same effect is obtained as was obtained with relay 2'! in Fig. 1, that is, windings 5| and 52 are connected in opposition so that signals transmitted from other subscribers stations will not actuate the local recording or signaling apparatus. The secondary windings and 56 are connected through lines 51 and to the vacuum tube amplifier 64 which is in turn connected to the slow release signal operating relay 68. When the impulse wheel 32 is operated by the watchman, contacts 35 and 36 ground the line at 38 and also open the line to operate the central office equipment. The transformer will then become operative since the positive ground signal pulse is transmitted through only winding 5| and thereby energizes the windings 55 and 56 of transformer 50. These windings in turn impress a positive pulse across resistance 6| to ground 62 to bias the amplifier In this case, however, the coil 230 is en- 64 to an operative condition and thereby energize slow release relay 68. The armature 69 of relay 68 in turn operates to energize recording or other indicating apparatus connected to circuit l8. Relay 68 is of the slow release type because the output of the tube 64 is only a pulse and the armature B8 would'quickly drop off. Furthermore, when ground is removed at the signal wheel, a second pulse occurs of opposite direction to the first, the grid becoming less positive and the armature 69 tending to drop ofi. In view of the above, the relay 68 must be slow to release.

Fig. 3 shows a different modification of a subscriber circuit wherein a Wheatstone bridge is substituted for the dififerential relay 21. The impulsing mechanism 32 is connected to lines 23 and 25 through the Wheatstonebridge which com.- prises resistances '88, BI, .52 and 83. Resistances 89 and 8! maybe of the order of one megohm each while resistances 812 and 83 may be of the order of two ohms each. Amplifier 54 is connected to the midpoint of resistances '80 and 8! by line 85 and to the two resistances 82 and 83 by the conductor 85. Thus, when a signal is transmitted from another substation through resistances 88 and 8'! the bridge will remain bal anced and no signal will be impressed on amplifier 54. However, when the transmitter vwheel 32 is operated, a ground signal will be transmitted through resistance 82 to unbalance thebridge circuit and therefore impress a potential on resistance 5i and, on the grid of amplifier. which in turn operates slow release relay 68, armature 53 and the recording or indicating apparatus in the subscriber's premises which is connected to the circuit m. In Figs. 2 and 3, other transmitters may be connected across circuit 59, as shown in Fig. 1, so that each subscriber will have a plurality of transmitters. Relay 68 must also be slow to release in the circuit shown in Fig. 3 because the relay armature 69 would tend to drop off after the break wheel opens the line and the grid'of tube 54 becomes less positive.

In all of the systems illustrated on the drawings, the transmitters 32, E32, 232 et cetera, may .be automatically operated in a manner obvious to those skilled in the art in response to any'condition or operation whichit is desired to supervise, such as fire conditions, the opening or closing of valves and the like.

From the above description it is evident that this invention provides a McCulloh signaling system wherein a plurality of subscribers are connected to a single transmission line and where each subscriber has a recording or indication of his own signals to the exclusion of all other sub-V scribers signals. Other modifications of this invention may be made in the construction and arrangernent of parts without departing from the spirit of the invention set forth in the appended claims.

. I claim:

1. In a signal system, a central station, a plurality of substations, a line connecting said substations to said central station, each of said substations comprising a differential relay having a pair of oppositely wound coils connected in series with said line, a plurality of pairs of contacts connected in series with said coils, means for actuating said contacts to ground and break said line through one of said coils and a signal adapted to be energized by said grounded coil.

2. In combination, a central station including an indicator, atransmission line connected to the central station, a plurality of substations connected in the transmissionline, transmitters connected in said substations for transmitting tothe line at each substation for counteracting the effect of the local indicator controlling means when line signals are initiated at another sub station.

3. In a signal system, a central station, a

transmission line connected thereto, a plurality of subscriber substations connected to said line, each station comprising a plurality of transmitter wheels, a pair of contacts adapted to be controlled by each transmitter wheel and a differential relay, each coil of which is connected in series with said contacts andsaid line,.signal means connected to each of said relays and means forgrounding onecoil of said relay whereby the local signal means will be operated and other subscribers signal means will not be operated.

4. In a signal system, a central station, a plurality of substations, a transmission line connecting said substations to the central station, a transmitter wheel in each substation, a ground connection to each of said wheels, a pair of contactsconnected in said line and controlled by said wheels to break said line and ground one side thereof, a differentially wound relay in one of said mission line connected thereto, a plurality of substations connected to said line, each station substations each of'the coilsof which are serially connected in said line and to one of said contacts a line connecting said substations to said central station, each of said substations comprising a differential relay having a pair of'oppositely wound coils connected'in series with said line, a

plurality of pairs of contacts connected in series with said coils, impulse means for grounding and breaking said line through one of said coils to operate said recorders at the central station and a signal adapted to be energized by said grounded coil.

6. Ina signal system, a central station, a transcomprising a transmitter for sending signals to the central oflice, a local signal in at least one substation, means in said one substation forcontrollingthe local signal comprising the primary coil of atransformer connected in said line and to said transmitter and a secondary coil connected to the local signaland means for counter acting the effect of said primary coil comprising a secondoppositely-wound coil connected in said line whereby line signals originatingin another substationdo not operatethe local signal.

'7. In a signal system, a' central station adapted for 'McCulloh operation, a transmission line connected thereto, a plurality of substations connected to said line, each station comprising a plurality of transmitter Wheels, a pair of contacts adapted to be controlled by each transmitter wheel and a transformer connected to said transmission line, said transformer comprising a pair of oppositely wound primary coils connectedto said contacts, a pair of secondary'coils, an amplifier connected to said secondary coils and means connected to said amplifier for operating a local signal, H I 8. In a signal system, acentralstatioma transmission line connected thereto and -a plurality of substations connected to said line,each substation comprising a transmitter for sendingsignals-to the central station and at least one of said substations also comprising abalanced Wheatstone bridge-connected at two of its conjugate points to saidline, a local signal connected across the other two conjugate points of said bridge whereby signals initiatedat other substations do not operate the local signal, the transmitter of said substation being connected in one leg of said bridge whereby locally transmitted signals unbalance said bridge and operate the local signal.

'9. In combination, a central ofiice including an indicator, a transmission line connected to the central office; a plurality of substationsconnected in the transmission line for transmitting signals to actuate the indicator, a local signal indicator in each substation, means in the transmission line and in the substation energized by local signals for-controlling the local, signal indicator in response to locally transmitted signals and additional means in the line at each'substationv for counteracting the efiect of the first means, when the line signals, are initiated in another; substation."

R. F. SPANIER. 

